Fluid Machine

ABSTRACT

A fluid machine ( 14, 102, 108 ) includes a plurality of fluid units ( 16, 20 ) each having a rotator ( 40, 66 ) and configured to let in and out a working fluid as the rotator ( 40, 66 ) rotates, and a drive shaft ( 72 ) to which the rotators ( 40, 66 ) of the fluid units ( 16, 20 ) are coupled, wherein an Oldham coupling ( 85 ) is arranged at a shaft section of the drive shaft ( 72 ) located between the rotators ( 40, 66 ).

TECHNICAL FIELD

The present invention relates to fluid machines, and more particularly, to a fluid machine suitable for use in a Rankine cycle of a waste heat utilization apparatus for a motor vehicle.

BACKGROUND ART

A Rankine cycle constituting a waste heat utilization system of an internal combustion engine, such as an engine of a motor vehicle, has a circulation path through which a working fluid (heat medium) is circulated. A pump, an evaporator (heat exchanger), an expander and a condenser are inserted in the circulation path in order.

The pump is driven by an electric motor, for example, to circulate the working fluid. The working fluid receives waste heat when passing through the evaporator and is caused to expand in the expander. When the working fluid is expanded, the heat energy of the working fluid is converted to torque. The torque is output to outside and used to rotate a fan for air-cooling the condenser, for example.

Patent Document 1 discloses, as a fluid machine suited for such a Rankine cycle, a fluid machine in which a pump, an expander and a motor share a single drive shaft.

PRIOR ART LITERATURE Patent Document

Patent Document 1: Japanese Laid-open Patent Publication No. 2005-30386

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

During manufacture of a fluid machine provided with a plurality of fluid units like the aforementioned one, individual fluid units are separately evaluated for their operation, and the fluid units satisfying evaluative standards are assembled together to obtain a final fluid machine, thereby improving the production efficiency of the fluid machine.

In the fluid machine of Patent Document 1, however, since the drive shaft is constituted by a single member, it is difficult to evaluate the operations of the individual fluid units separately from each other.

Specifically, when the operation of the expander mechanism is evaluated, torque required to rotate the drive shaft in an unloaded state is measured. However, since the rotator of the pump also rotates as the drive shaft is rotated, the accuracy of the unloaded torque measurement lowers. Consequently, the expander cannot be properly evaluated, posing a problem that performance of the fluid machine cannot be ensured.

Also, in case the expander or the pump fails, the whole fluid machine needs to be disassembled to repair or replace the faulty unit, and in the worst case, the fluid machine itself has to be scrapped because of failure of either one of the expander and the pump. Accordingly, the fluid machine of Patent Document 1 still requires improvement in production efficiency and maintainability.

Further, fluid machines having a plurality of fluid units coupled to each other tend to have an increased length along the axis of the drive shaft and thus an increased size. In the above conventional technique, however, no special consideration is given to reduction in size of the fluid machine.

The present invention was created in view of the above circumstances, and an object thereof is to provide a fluid machine which is improved in production efficiency and maintainability while at the same time ensuring performance and which also is reduced in size.

Means for Solving the Problems

A fluid machine according to the present invention comprises: a plurality of fluid units each including a rotator and configured to let in and out a working fluid as the rotator rotates; and a drive shaft to which the rotators of the plurality of fluid units are coupled, wherein an Oldham coupling is arranged at a shaft section of the drive shaft located between the rotators.

Preferably, the Oldham coupling includes a slider, the slider has an engaging portion for engagement with the shaft section and a body provided with the engaging portion, and the slider is received in a receiving hole formed in the shaft section.

The plurality of fluid units preferably include an expansion unit, and the expansion unit includes a first rotator and is configured such that as the first rotator rotates, the expansion unit admits the working fluid, then expands the working fluid, and delivers the expanded working fluid.

Preferably, the plurality of fluid units include a pump unit, and the pump unit includes a second rotator and is configured such that as the second rotator rotates, the pump unit draws in the working fluid, then raises pressure of the working fluid, and discharges the working fluid.

Also, preferably, the plurality of fluid units include a compression unit, and the compression unit includes a third rotator and is configured such that as the third rotator rotates, the compression unit draws in the working fluid, then compresses the working fluid, and delivers the compressed working fluid.

Preferably, the fluid machine further comprises an electric power generation unit including a fourth rotator coupled to the drive shaft, and the electric power generation unit is configured to generate electric power as the fourth rotator rotates.

Preferably, the fluid machine further comprises a power generation-drive unit including a fifth rotator coupled to the drive shaft, and the power generation-drive unit is configured to generate electric power as the fifth rotator rotates, and to drive the drive shaft when the fifth rotator is rotated by externally supplied electric power.

Preferably, the fluid machine further comprises a motive power transmission unit coupled to the drive shaft and configured to transmit motive power between the drive shaft and an external device.

Advantageous Effects of the Invention

According to the present invention, the Oldham coupling is arranged at the shaft section of the drive shaft located between the rotators. Thus, during manufacture of the fluid machine, the fluid units are detached from each other at the Oldham coupling, and the individual fluid units are separately evaluated for their operation. Since the operation of each fluid unit can be properly evaluated, it is possible to improve production efficiency while at the same time ensuring performance of the fluid machine.

Also, according to the present invention, in case any one of the fluid units fails, the faulty unit alone can be detached at the Oldham coupling for repair or replacement. Thus, it is unnecessary to disassemble the whole fluid machine for repair or replacement of the faulty unit, whereby maintainability of the fluid machine can be improved.

The Oldham coupling is simple in structure, compared with a coupling structure using splines or the like, and accordingly, centering operation can be relatively easily carried out when the individual fluid units are evaluated for their operation, thus contributing to further improvement in the production efficiency of the fluid machine.

Also, the Oldham coupling on one hand permits radial displacement of the shaft sections and on the other hand reduces error in rotational angle accompanying shaft misalignment (eccentricity, angular displacement), whereby the rotational angle can be transferred with high accuracy. Since misalignment of the shaft sections caused when the fluid units are coupled to each other is tolerated, performance of the fluid machine can be ensured.

Further, according to the present invention, it is possible to prevent the slider from dropping off when the shaft sections are coupled to each other with the slider therebetween, and accordingly, to prevent deterioration in workability during assembling of the fluid machine. Specifically, the slider can be effectively prevented from dropping off during the centering operation performed when the individual fluid units are evaluated for their operation. Since the centering operation can be carried out with ease, the production efficiency of the fluid machine can be improved.

According to the present invention, moreover, the slider remains buried in the shaft section after the fluid machine is assembled. Thus, the length of the shaft section, and accordingly, the length of the drive shaft can be shortened by an amount equal to the axial length of the slider, thus permitting reduction in size of the fluid machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic configuration of an automotive waste heat utilization apparatus provided with a fluid machine according to a first embodiment.

FIG. 2 is a schematic longitudinal sectional view of the fluid machine applied to the apparatus of FIG. 1.

FIG. 3 is a schematic longitudinal sectional view of a fluid machine according to a second embodiment.

FIG. 4 is a schematic longitudinal sectional view of a fluid machine according to a third embodiment.

FIG. 5 is a schematic longitudinal sectional view of a fluid machine according to a fourth embodiment.

FIG. 6 is a perspective view illustrating a receiving hole shown in FIG. 5.

FIG. 7 is a perspective view of a slider shown in FIG. 5.

FIG. 8 is a perspective view illustrating an end face of a driven shaft section shown in FIG. 5.

FIG. 9 is a perspective view illustrating a receiving hole constituting an Oldham coupling according to a fifth embodiment.

FIG. 10 is a plan view illustrating a state in which a hub is received in a groove cut in the bottom of the receiving hole shown in FIG. 9.

FIG. 11 is a plan view illustrating a state in which the hub is slightly rotated in a circumferential direction of the shaft section of FIG. 9 when the fluid machine is assembled.

MODE OF CARRYING OUT THE INVENTION

FIG. 1 illustrates a waste heat utilization apparatus 1 using a fluid machine 14 according to a first embodiment. The waste heat utilization apparatus 1 recovers heat from exhaust gas emitted from an automotive engine (internal combustion engine) 10, for example. To this end, the waste heat utilization apparatus 1 is provided with a Rankine cycle 12 having a circulation path 13 for circulating a working fluid (heat medium) therethrough. The circulation path 13 is constituted, for example, by a tube or a pipe.

A pump unit (fluid unit) 16 of the fluid machine 14 is inserted in the circulation path 13 to cause the working fluid to flow. Further, a heater 18, an expansion unit (fluid unit) 20 of the fluid machine 14, and a condenser 22 are successively arranged downstream of the pump unit 16 in the mentioned order in the direction of flow of the working fluid. That is, the pump unit 16 draws in the working fluid from the condenser side, raises the pressure of the working fluid thus drawn therein, and discharges the working fluid toward the heater 18. The working fluid discharged from the pump unit 16 is in a low-temperature, high-pressure liquid state.

The heater 18, which is a heat exchanger, has a low-temperature flow path 18 a forming part of the circulation path 13, and a high-temperature flow path 18 b capable of exchanging heat with the low-temperature flow path 18 a. The high-temperature flow path 18 b is inserted in an exhaust pipe 24 extending from the engine 10, for example. Thus, when passing through the heater 18, the working fluid in the low-temperature, high-pressure liquid state receives heat from the exhaust gas emitted from the engine 10. As a result, the working fluid is heated to a high-temperature, high-pressure superheated vapor state.

The expansion unit 20 of the fluid machine 14 allows the working fluid in the superheated vapor state to expand, so that the working fluid turns into a high-temperature, low-pressure superheated vapor state.

The condenser 22, which is a heat exchanger, condenses the working fluid delivered from the expansion unit 20, by allowing heat to transfer from the working fluid to ambient air, so that the working fluid turns into a low-temperature, low-pressure liquid state. Specifically, an electric fan (not shown) is arranged near the condenser 22, and the working fluid is cooled by air currents flowing thereto from the electric fan or from the front of the vehicle. The working fluid thus cooled by the condenser 22 is again drawn into the pump unit 16 to be circulated through the circulation path 13.

The expansion unit 20 not only expands the working fluid but is capable of converting heat energy of the working fluid to torque (turning force) and outputting the torque. In addition to the pump unit 16, an electric power generation unit 26 is coupled to the expansion unit 20 so as to be able to utilize the torque output from the expansion unit 20. The power generation unit 26 is connected with a suitable electric load 28 that consumes or stores the generated electric power, for example, a battery.

The fluid machine 14 also includes a motive power transmission unit 30 for inputting/outputting torque. The power transmission unit 30 is, for example, an electromagnetic clutch. The electromagnetic clutch is operated under the control of an ECU (Electronic Control Unit) 31 and is capable of intermittently transmitting torque.

More specifically, as shown in FIG. 2, the expansion unit 20, the power generation unit 26 and the pump unit 16 are serially coupled in the mentioned order by a drive shaft 72. The drive shaft 72 has a driving shaft section 72A located inside the power generation unit 26 and the expansion unit 20, a driven shaft section 72B located inside the pump unit 16, and a slider 87 located between the shaft sections 72A and 72B.

The expansion unit 20 is a scroll-type expander having a revolving mechanism 21 as a drive unit. The expansion unit 20 includes a cup-shaped casing 32 (expansion unit casing) having an opening substantially closed by a partition wall 34, and a through hole is formed in the center of the partition wall 34.

A fixed scroll 36 is secured to the inside of the expansion unit casing 32, and a high-pressure chamber 38 is defined behind the fixed scroll 36. The high-pressure chamber 38 communicates with the heater 18 through an inlet port formed in the expansion unit casing 32 and a part of the circulation path 13 connected to the inlet port.

A movable scroll (rotator, first rotator) 40 is arranged on a front side of the fixed scroll 36 so as to engage with the fixed scroll 36. An expansion chamber 42 for expanding the working fluid is defined between the fixed scroll 36 and the movable scroll 40, and a low-pressure chamber 44 for admitting the expanded working fluid is defined around the movable scroll 40. An introduction hole 46 is formed through substantially the center of a base plate of the fixed scroll 36, and the expansion chamber 42 communicates, at a portion thereof located at the radial center of the fixed and movable scrolls 36 and 40, with the high-pressure chamber 38 through the introduction hole 46.

As the working fluid expands in the radially central portion of the expansion chamber 42, the volumetric capacity of the expansion chamber 42 increases and the expansion chamber 42 moves radially outward along spiral walls of the fixed and movable scrolls 36 and 40. The expansion chamber 42 finally communicates with the low-pressure chamber 44, so that the expanded working fluid flows into the low-pressure chamber 44. The low-pressure chamber 44 communicates with the condenser 22 through an outlet port, not shown, and a part of the circulation path 13 connected to the outlet port.

As the working fluid expands as stated above, the movable scroll 40 is caused to make orbiting motion relative to the fixed scroll 36, and the orbiting motion is converted to rotary motion by the revolving mechanism 21.

Specifically, a boss protrudes integrally from the back surface of a base plate of the movable scroll 40, and an eccentric bush 50 is relatively rotatably arranged inside the boss with a needle bearing 48 therebetween. A crankpin 52 projects eccentrically from a disk 54 and is inserted through the eccentric bush 50. A shaft section 56 projects from a side of the disk 54 opposite the crankpin 52 and extends coaxially with the disk 54. The shaft section 56 is rotatably supported by the partition wall 34 with a radial bearing 58 such as a ball bearing therebetween, and is coupled to the driving shaft section 72A through a one-way clutch 95. That is, the movable scroll 40 is rotatably supported by the partition wall 34, the orbiting motion of the movable scroll 40 is converted to rotary motion of the shaft section 56, and the rotary motion of the shaft section 56 is transmitted to the driving shaft section 72A.

The revolving mechanism 21 includes, for example, a ball coupling 60 for preventing the movable scroll 40 from rotating about its own axis while making orbiting motion and also for bearing thrust load. The ball coupling 60 is arranged between a radially outward portion of the base plate of the movable scroll 40 and a corresponding portion of the partition wall 34 facing the base plate.

When the revolving mechanism 21 is in operation, the fixed and movable scrolls 36 and 40 are brought into sliding contact with each other with a slight gap therebetween.

Specifically, the fixed and movable scrolls 36 and 40 are respectively constituted by the base plates 36 a and 40 a, and spiral wraps 36 b and 40 b protruding integrally from the inner surfaces of the respective base plates 36 a and 40 a. A tip seal 37 is attached to the tip of each of the spiral wraps 36 b and 40 b, and the spiral wraps 36 b and 40 b are brought into sliding contact, at their tip seals 37, with the base plates 40 a and 36 a facing the respective spiral wraps 36 b and 40 b with a slight gap therebetween. Spiral walls of the spiral wraps 36 b and 40 b locally come into sliding contact with each other, so that the expansion chamber 42 of spiral form is created around the axes of the base plates 36 a and 40 a.

The gap between the spiral wrap 36 b and the opposing base plate 40 a and the gap between the spiral wrap 40 b and the opposing base plate 36 a, that is, the gap between the fixed and movable scrolls 36 and 40 is secured by coupling faces of the expansion unit casing 32 and partition wall 34. Specifically, the coupling faces are constituted by an end wall 32 a of the expansion unit casing 32 and an end wall 34 a of the partition wall 34, and an annular shim 39 of metal, for example, is interposed between the end walls 32 a and 34 a. When the expansion unit casing 32 and the partition wall 34 are coupled together by connecting bolts, not shown, a shim 39 with a suitable thickness is selected or the number of shims to be used is varied to adjust a length of the gap between the fixed and movable scrolls 36 and 40 so that during operation of the expansion unit 20, pressing force exerted on the fixed scroll 36 in the axial direction of the drive shaft 72 by the movable scroll 40 may be uniformly and reliably borne by the expansion unit casing 32.

The gap length between the fixed and movable scrolls 36 and 40 is adjusted for the purpose of evaluating operation of the expansion unit 20 to determine whether or not the movable scroll 36 smoothly orbits with respect to the fixed scroll 40.

The gap length adjustment is carried out in the manner described below. The fixed and movable scrolls 36 and 40 are temporarily combined together, and a torque sensor (evaluation instrument) such as a motor, not shown, is connected to the driving shaft section 72A. Then, a load torque required to rotate the driving shaft section 72A is measured, and the gap length between the fixed and movable scrolls 36 and 40 is estimated from the measured load torque. If the estimated gap length between the fixed and movable scrolls 36 and 40, which is estimated from the measured load torque, is between upper- and lower-limit values defining an allowable gap range, the fixed and movable scrolls 36 and 40 are permanently combined together. Thus, the gap length between the fixed and movable scrolls 36 and 40 is controlled by the aforementioned load torque inspection, which is one step of manufacturing process of the fluid machine 14.

The pump unit 16, on the other hand, is a trochoidal type pump, for example, but may alternatively be an external gear pump. The pump unit 16 includes a cylindrical casing (pump unit casing 62) opening at both ends, and a pair of annular covers 64 is arranged inside the pump unit casing 62 with a predetermined space therebetween. An inner gear (rotator, second rotator) 66 is rotatably arranged between the covers 64, and an outer gear 68 is fixed so as to surround the inner gear 66.

A pump chamber 70 is defined between the inner and outer gears 66 and 68, and as the inner gear 66 is rotated, the pressure of the working fluid in the pump chamber 70 rises. The working fluid is drawn into the pump chamber 70 from the condenser 22 through a suction port, not shown, and a part of the circulation path 13 connected to the suction port. Then, the working fluid of which the pressure has been raised in the pump chamber 70 is discharged toward the heater 18 through a discharge port, not shown, and a part of the circulation path 13 connected to the discharge port.

The inner gear 66 is secured to the driven shaft section 72B so as to be rotatable together therewith.

An electromagnetic clutch serving as the motive power transmission unit 30, described later, is coupled to one end of the driven shaft section 72B, and the shaft section 56 of the revolving mechanism 21 is coupled to the other end of the drive shaft 72 through the one-way clutch 95.

The drive shaft 72 includes an Oldham coupling 85 arranged at the shaft section between the movable scroll 40 and the inner gear 66.

The Oldham coupling 85 is a well-known coupling having projections fitted in respective grooves and capable of transmitting rotary driving force while allowing the projections to slide along the respective grooves. The drive shaft 72 has a hub 72 a, as one projection, integrally protruding from or joined to the slider (87)-side end face of the driving shaft section 72A located on the same side as the power generation unit 26 and the expansion unit 20. Also, the drive shaft 72 has another hub 72 b, as the other projection, integrally protruding from or joined to the slider (87)-side end face of the driven shaft section 72B located on the same side as the pump unit 16.

The slider 87 is interposed between the hubs 72 a and 72 b. The slider 87 includes a columnar body 91 having end faces facing the hubs 72 a and 72 b, respectively, and grooves (engaging portions) 87 a and 87 b are cut in the respective end faces of the body 91 and extend in radial directions of the drive shaft 72 perpendicularly to each other. The torque sensor used for evaluating operation of the expansion unit 20 is connected to the hub 72 a.

The slider 87 is positioned such that the hubs 72 a and 72 b are received in the respective grooves 87 a and 87 b. Thus, the Oldham coupling 85 on one hand permits radial displacement of the drive shaft 72 between the driving and driven shaft sections 72A and 72B, and on the other hand reduces error in rotational angle of the drive shaft 72 caused by misalignment accompanying eccentricity or angular displacement between the driving and driven shaft sections 72A and 72B, whereby the rotational angle of the driving shaft section 72A can be transferred with high accuracy to the driven shaft section 72B.

The drive shaft 72 provided with the Oldham coupling 85 penetrates through the covers 64, the pump unit casing 62, as well as lid members 74 and 75 fixed to respective open ends of the pump unit casing 62. The lid member 74 has a cylindrical portion 76 and a flange 78, and the lid member 75 has a cylindrical portion 77 and a flange 79. The flanges 78 and 79 are joined to the respective open ends of the pump unit casing 62.

Radial bearings 79 and 80 are arranged inside the cylindrical portion 76 and located at opposite ends, respectively, of the cylindrical portion 76, and a radial bearing 89 is arranged inside the cylindrical portion 77. The cylindrical portions 76 and 77 rotatably support the drive shaft 72 with the use of the radial bearings 79, 80 and 89. A shaft seal member 81 such as a lip seal or the like is arranged inside the cylindrical portion 76 and seals the interior of the cylindrical portion 76 in an airtight fashion.

The drive shaft 72 has one end projecting from the cylindrical portion 76 and coupled with the electromagnetic clutch serving as the motive power transmission unit 30.

Specifically, the motive power transmission unit 30 includes a rotor 83 arranged around the cylindrical portion 76 with a radial bearing 82 therebetween, and a pulley 84 is fixed to the outer peripheral surface of the rotor 83. A belt 86, indicated by the dot-dash line in the figure, is passed around the pulley 84 and a pulley of the engine 10 so that the pulley 84 and the rotor 83 can rotate together when motive power is transmitted thereto from, for example, the engine 10. A solenoid 97 is arranged inside the rotor 83 and generates a magnetic field when electric power is supplied thereto from the ECU 31.

An annular armature 88 is arranged near the outer end face of the rotor 83 and coupled to a boss 92 by elastic members 90 such as leaf springs. The boss 92 is splined to the one end of the drive shaft 72, so that the armature 88 is rotatable together with the drive shaft 72. When a magnetic field is generated by the solenoid 97, the armature 88 is attracted to the end face of the rotor 83 against the urging force of the elastic members 90, with the result that motive power is transmittable between the rotor 83 and the armature 88.

The electric power generation unit 26 includes a cylindrical casing (power generation unit casing) 93 held between the partition wall 34 and the pump unit casing 62. The expansion unit casing 32, the partition wall 34, the power generation unit casing 93, the pump unit casing 62 and the lid member 74 are coupled together to constitute a housing for the fluid machine 14.

The other end of the drive shaft 72 extends up to the through hole in the partition wall 34 and is rotatably supported by the partition wall 34 with a needle bearing 94 therebetween. The one-way clutch 95 as a coupling member is securely fitted in the other end of the drive shaft 72, and the other end of the drive shaft 72 and the shaft section 56 of the revolving mechanism 21 are coupled to each other by the one-way clutch 95.

While the shaft section 56 and the drive shaft 72 are rotating in an identical direction, the one-way clutch 95 cuts off motive power transmission between the shaft section 56 and the drive shaft 72 if the rotating speed of the shaft section 56 is lower than that of the drive shaft 72, and permits the motive power transmission between the shaft section 56 and the drive shaft 72 if the rotating speed of the shaft section 56 becomes higher than that of the drive shaft 72, so that the shaft section 56 and the drive shaft 72 rotate together.

A rotor (fourth rotator) 96 is fixed on a portion of the drive shaft 72 extending inside the power generation unit casing 93. The rotor 96 comprises permanent magnets, for example, and is positioned coaxially with the shaft section 56 and the inner gear 66.

A stator is fixed to the inner peripheral surface of the power generation unit casing 93 so as to surround the rotor 96. The stator includes a yoke 98 and, for example, three coil windings 100 wound on the yoke 98. The coil windings 100 are so wired as to generate a three-phase alternating current when the rotor 96 is rotated, and the generated alternating current is supplied to the external load 28 through an outgoing line, not shown.

The electric power generation unit 26 does not function as an electric motor, and accordingly, the shape of the yoke 98, the number of turns of the coil windings 100 and the like are selected so that the power generation efficiency may be as high as possible.

In the following, the manner of how the aforementioned waste heat utilization apparatus 1 for a vehicle is used will be explained in conjunction with the operation of the fluid machine 14 and Rankine cycle 12.

<Starting Operation>

When the motive power transmission unit 30 is switched on by the ECU 31 to start operation of the Rankine cycle 12, the motive power of the engine 10 is input to the drive shaft 72. As the drive shaft 72 rotates, the inner gear 66 of the pump unit 16 is rotated, so that the pump unit 16 draws in the working fluid from the upstream side, then raises the pressure of the working fluid, and discharges the working fluid to the downstream side.

As a result of the circulation of the working fluid through the circulation path 13, the working fluid is heated in the heater 18 and then is expanded in the expansion unit 20.

Immediately after the start of the Rankine cycle 12, the pressure of the working fluid in the circulation path 13 is low, and therefore, the orbiting speed of the movable scroll 44, in other words, the rotating speed of the shaft section 56 of the revolving mechanism 21 is lower than that of the drive shaft 72. Accordingly, the one-way clutch 95 cuts off the power transmission between the shaft section 56 and the drive shaft 72.

<Autonomous Operation and Electric Power Generation>

Once the pressure of the working fluid in the circulation path 13 becomes sufficiently high after the start of the Rankine cycle 12, the rotating speed of the shaft section 56 of the revolving mechanism 21 tends to become higher than that of the drive shaft 72. When the rotating speed of the shaft section 56 of the revolving mechanism 21 in a free state becomes higher than that of the drive shaft 72, the one-way clutch 95 is locked, with the result that the shaft section 56 and the drive shaft 72 rotate together.

When the torque transmitted from the shaft section 56 to the drive shaft 72 becomes high enough to operate the pump unit 16, the ECU 31 switches off the motive power transmission unit 30 to cut off the supply of the motive power from the engine 10. As a result, the mode of operation of the fluid machine 14 shifts to autonomous operation wherein the torque generated by the expansion unit 20 is utilized to operate the pump unit 16.

On the other hand, as the drive shaft 72 rotates, the rotor 96 of the electric power generation unit 26 is rotated, so that the power generation unit 26 generates an alternating current. The alternating current is supplied to the load 28 and stored in or consumed by the load 28. The load 28 may include a rectifier for converting the alternating current to a direct current.

<Regenerative Brake>

After the operation mode of the fluid machine 14 is shifted to the autonomous operation, the load on the engine 10 is lower than before. When the vehicle is braked or decelerated, the ECU 31 may switch on the motive power transmission unit 30 to engage the electromagnetic clutch.

In this case, the fluid machine 14 functions as a regenerative brake, whereby not only the engine 10 is applied with an auxiliary load for deceleration but the kinetic energy of the vehicle is converted to electric power by the power generation unit 26.

<Other Possible Operation>

Instead of shifting the operation mode of the fluid machine 14 to the autonomous operation, torque may be output from the fluid machine 14 to the engine 10. Specifically, out of the torque generated by the expansion unit 20, a surplus torque that remains after the consumption by the pump unit 16 and the electric power generation unit 26 may be output to the engine 10 through the motive power transmission unit 30.

As described above, in the fluid machine 14 of the first embodiment, the drive shaft 72 is coupled with the movable scroll 40 through the shaft section 56 and is also coupled with the inner gear 66 of the pump unit 16, and the Oldham coupling 85 is provided at the shaft section of the drive shaft 72 located between the movable scroll 40 and the inner gear 66. Thus, during manufacture of the fluid machine 14, the expansion unit 20 can be detached from the pump unit 16 at the Oldham coupling 85 and can be separately evaluated for its operation. Since the operation of the expansion unit 20 can be properly evaluated, it is possible to improve production efficiency while at the same time ensuring performance of the fluid machine 14.

In cases where the load torque of the drive shaft 72 is measured to evaluate operation of the revolving mechanism 21, the inner gear 66 of the pump unit 16 rotates as the drive shaft 72 is rotated, and friction accompanying the rotation of the inner gear 66 causes error in the measurement results of the load torque. In the foregoing embodiment, however, such a situation does not occur, and therefore, operation of the expansion unit 20 can be properly evaluated.

In the event that the pump unit 16 fails, the pump unit 16 alone can be detached at the Oldham coupling 85 to be repaired or replaced with a new one. It is unnecessary to disassemble the whole fluid machine 14 for repair or replacement of the pump unit 16, whereby maintainability of the fluid machine 14 can be improved.

Further, since the Oldham coupling 85 is relatively simple in structure, centering of the torque sensor can be performed relatively easily when the torque sensor is connected to the hub 72 a in order to evaluate the operation of the expansion unit 20, thus further improving the production efficiency of the fluid machine.

Furthermore, the Oldham coupling 85 on one hand permits radial displacement of the shaft sections and on the other hand reduces error in the rotational angle accompanying shaft misalignment (eccentricity, angular displacement), whereby the rotational angle can be transferred with high accuracy. Since misalignment of the shaft sections caused when the units 16 and 20 are coupled to each other is tolerated, performance of the fluid machine 14 can be ensured.

FIG. 3 illustrates a fluid machine 102 according to a second embodiment. For elements identical with those of the fluid machine 14 of the first embodiment, identical reference signs are used and description of such elements is omitted, or the reference signs themselves are omitted.

The fluid machine 102 is not provided with the motive power transmission unit 30, and the inner gear 66, not shown in FIG. 3, of the pump unit 16 is coupled to the end of the driven shaft section 72B located opposite the Oldham coupling 85.

Also, the fluid machine 102 is not provided with the pump unit casing 62, and the pump unit 16 is fastened to the open end of the power generation unit casing 93 by two through bolts 104 penetrating through the covers 64. The through bolts 104 are inserted from outside the fluid machine 102 into respective holes located diagonally with respect to the covers 64.

On the other hand, the covers 64 are fastened together by two connecting bolts 106. The connecting bolts 106 are inserted from outside the fluid machine 102 into respective holes located in a diagonal relationship different from that of the through bolts 104. Thus, the expansion unit casing 32, the partition wall 34, the power generation unit casing 93 and the covers 64 are coupled together to constitute a housing for the fluid machine 102.

Further, in the fluid machine 102, the Oldham coupling 85 is located closer to the pump unit 16 than the radial bearing 89 of the drive shaft 72 is.

Thus, where the fluid machine 102 is not provided with the motive power transmission unit 30, the housing of the fluid machine 102 can be simplified in structure.

Also, the pump unit 16 is fixed by the through bolts 104 inserted from outside the fluid machine 102. Since the through bolts 104 and the connecting bolts 106 can be inserted from the same side in the same direction, the production efficiency of the fluid machine 102 can be further improved.

FIG. 4 illustrates a fluid machine 108 according to a third embodiment. For elements identical with those of the fluid machines 14 and 102 of the first and second embodiments, identical reference signs are used and description of such elements is omitted, or the reference signs themselves are omitted.

The fluid machine 108 is not provided with the electric power generation unit 26, and accordingly, the pump unit casing 62 is fastened to the expansion unit casing 32 with the partition wall 34 therebetween.

Also, the fluid machine 108 is not provided with the lid member 74. Instead, the pump unit casing 62 extends up to a position corresponding to the lid member 74, and the expansion unit casing 32, the partition wall 34 and the pump unit casing 62 are coupled together to constitute a housing for the fluid machine 108. The Oldham coupling 85 is located inside the pump unit casing 62.

Further, the pump unit 16 is fastened to the pump unit casing 62 by a plurality of through bolts 109 penetrating through the lid member 75. The through bolts 109 are inserted from inside the pump unit casing 62.

Thus, where the fluid machine 108 is not provided with the electric power generation unit 26, the housing of the fluid machine 108 can be simplified in structure, whereby the production efficiency of the fluid machine 108 can be further improved.

The pump unit 16 is fastened to the pump unit casing 62 from inside the pump unit casing 62, that is, from inside the fluid machine 108. Compared with the first embodiment, the number of seals of the housing of the fluid machine 108 can be reduced by one. It is therefore possible to reduce the possibility of the working fluid leaking out from the housing, further improving reliability of the fluid machine 108.

FIG. 5 illustrates a fluid machine 110 according to a fourth embodiment. For elements identical with those of the fluid machine 108 of the third embodiment, identical reference signs are used and description of such elements is omitted, or the reference signs themselves are omitted.

In the fluid machine 110, an Oldham coupling 112 is buried in the shaft section 56 of the drive shaft 72 protruding integrally from the side of the disk 54 opposite the crankpin 52 and extending coaxially with the disk 54.

The Oldham coupling 112 is configured as illustrated in FIGS. 6 to 8. The hub 72 b as a projection protrudes integrally from or is joined to the end face of the driven shaft section 72B of the drive shaft 72 located on the same side as the pump unit 16 (FIG. 8). A receiving hole 116 for a slider 114 of this embodiment is formed in the end face of the shaft section 56 located opposite the crankpin 52 (FIG. 6).

The slider 114 has a columnar body 111, and a hub (engaging portion) 114 a protrudes from an end face of the body 111 located on the same side as the receiving hole 116. Also, a groove (engaging portion) 114 b is formed in the other end face of the body 111 close to the hub 72 b so as to extend in a radial direction of the drive shaft 72 and perpendicularly to the hub 114 a (FIG. 7).

The receiving hole 116 has a groove 116 b formed in a bottom 116 a thereof, and the slider 114 is positioned with the hub 114 a fitted in the groove 116 a and with the groove 114 b receiving the hub 72 b. Thus, the Oldham coupling 112 on one hand permits radial displacement of the shaft section 56, that is, radial displacement of the drive shaft 72 between the driving and driven shaft sections 72A and 72B, and on the other hand reduces error in the rotational angle of the drive shaft 72, whereby the rotational angle of the driving shaft section 72A is transferred to the driven shaft section 72B with high accuracy.

The receiving hole 116 has a depth D nearly equal to an axial length L of the slider 114 excluding the hub 114 a, and accordingly, the slider 114, including the body 111 and the groove 114 b, is completely received in the receiving hole 116. When the driven shaft section 72B is connected to the driving shaft section 72A with the slider 114 therebetween, radial movement of the slider 114 is restricted by a wall surface 116 c of the receiving hole 116. That is, the receiving hole 116 has a hole diameter d1 slightly larger than a shaft diameter d2 of the slider 114. Thus, when the fluid machine 110 is assembled, the slider 114 can scarcely move in the receiving hole 116 in the radial direction, so that the slider 114 is engaged with the shaft section 56 not only by the groove 114 b but also by the body 111 fitted in the receiving hole 116.

With the fluid machine 110, it is possible to prevent the slider 114 from dropping off when the driven shaft section 72B is connected to the driving shaft section 72A with the slider 114 therebetween, and accordingly, to prevent deterioration in workability during assembling of the fluid machine 110. Specifically, the slider 114 can be effectively prevented from dropping off during the centering operation performed when the individual fluid units 16 and 20 are evaluated for their operation. Since the centering operation can be carried out more easily, the production efficiency of the fluid machine 110 can be further improved.

Further, the slider 114 remains buried in the shaft section 56 after the fluid machine 110 is assembled. Thus, the length of the driven shaft section 72B, and accordingly, the length of the drive shaft 72 can be shortened by an amount equal to the axial length L of the slider 114, thus permitting further reduction in size of the fluid machine 110.

FIG. 9 is a perspective view illustrating a receiving hole 120 constituting an Oldham coupling 118 of a fifth embodiment, and FIGS. 10 and 11 are plan views illustrating a state in which the hub 114 a is received in a groove 120 b formed in the bottom 120 a of the receiving hole 120. For elements identical with those of the fluid machine 110 of the fourth embodiment, identical reference signs are used and description of such elements is omitted, or the reference signs themselves are omitted.

In the fourth embodiment, the groove 116 b has two pairs of side faces 117 a, 117 c and 117 b, 117 d, as shown in FIG. 6, and the adjacent side faces 117 a, 117 b and 117 c, 117 d are smoothly connected to each other by rounded corners 119.

In the fifth embodiment, the groove 120 b is formed as shown in FIGS. 9 and 10 in such a manner that adjacent side faces 122 a, 122 b and 122 c, 122 d are connected to each other by stepped corners 124. The corners 124 are formed by arcuately cutting off the opposite ends of the two side faces 122 a and 122 c which extend in the longitudinal direction of the groove 120 b, among the side faces 122 a to 122 d, for example.

Thus, when the hub 114 a is received in the groove 120 b, right-angled edges 126 of the hub 114 a can be made not to come into contact with the corners 124, and escape spaces 128 are provided to allow the hub 114 a to move slightly in the longitudinal direction of the groove 120 b. The shape of the corners 124 is not limited to the aforementioned shape and the corners 124 may have any other shape insofar as the escape spaces 128 are provided.

In this fluid machine 110, the escape spaces 128 are provided at the corners 124 of the groove 120 b. Accordingly, when the fluid machine 110 is assembled, the hub 114 a is allowed to move slightly in the longitudinal direction of the groove 120 b, namely, in the radial direction of the shaft section 56, as indicated by arrows in FIG. 11. It is therefore possible to effectively tolerate axis misalignment of the drive shaft 72 between the driving and driven shaft sections 72A and 72B attributable to dimension error or assembling error of the fluid units 16 and 20, making it unnecessary to strictly control the dimension error and assembling error of the fluid machine 110 and thereby enabling further improvement in the production efficiency of the fluid machine 110.

The present invention is not limited to the first to fifth embodiments described above and may be modified in various ways though not specifically illustrated.

For example, the Oldham coupling 85 may be provided at a shaft section of the drive shaft 72 located between the expansion unit 20 and the electric power generation unit 26.

Also, with the partition wall 34 omitted, the expansion unit casing 32 may be directly joined to the pump unit casing 62 to increase the volumetric capacity of the expansion unit casing 32, and the Oldham coupling 85 may arranged in a region inside the expansion unit casing 32 where the working fluid exists in communication with the low-pressure chamber 44. In this case, the partition wall 34 and the radial bearing 58 are unnecessary, and since the fluid machine can be simplified in structure, the production efficiency of the fluid machine further improves.

Further, the Oldham coupling 85 may be subjected to surface hardening process such as nitriding. In this case, durability of the Oldham coupling 85 can be enhanced, making it possible to improve the reliability of the fluid machine.

Furthermore, the fluid machine may be configured such that the expansion unit 20 and the pump unit 16 are coupled to a compression unit (fluid unit) which, as a movable scroll (rotator, first rotator) thereof makes orbiting motion, draws in the working fluid, then compresses the working fluid, and delivers the compressed working fluid. Especially, in the case where the compression unit and the expansion unit 20 are coupled to each other, the revolving mechanism of the expansion unit 20 can be detached from that of the compression unit at the Oldham coupling 85 for evaluation of the operation of the individual units, thus further improving the production efficiency of the fluid machine.

Also, an oil feed passage may be formed in the drive shaft 72 to convey lubricating oil for lubricating the revolving mechanism. Where the compression unit and the expansion unit 20 are coupled to each other, in particular, the lubricating oil may be circulated through the oil feed passage to be supplied to both of the compression unit and the expansion unit 20. In this case, the revolving mechanisms of both units can be sufficiently lubricated.

In the first to third embodiments, the trochoidal type pump unit 16 is used, but the type of pump unit to be used is not particularly limited.

Also, the arrangement of the units, such as the pump unit 16, the electric power generation unit 26 and the expansion unit 20, is not particularly limited.

Further, in place of the electric power generation unit 26, a motor-generator (power generation-drive unit) which functions as an electric motor in addition to the power generation unit 26 may be used. The motor-generator has a rotor (fifth rotator) therein and has the function of generating electric power as the rotor rotates. When the rotor is rotated by externally supplied electric power, the motor-generator functions as a motor for rotating the drive shaft 72.

The buried structure of the fourth embodiment in which the slider 114 is buried in the shaft section 56 of the drive shaft 72 is of course applicable to the fluid machines of the first and second embodiments except the fluid machine of the third embodiment.

Furthermore, the fluid machine of the present invention is applicable to any refrigeration circuit in which a working fluid is circulated, besides the Rankine cycle 12 of the automotive waste heat utilization apparatus 1.

EXPLANATION OF REFERENCE SIGNS

14, 102, 108, 110 fluid machine

16 pump unit (fluid unit)

20 expansion unit (fluid unit)

26 electric power generation unit

30 motive power transmission unit

40 movable scroll (rotator, first rotator)

66 inner gear (rotator, second rotator)

72 drive shaft

85, 112 Oldham coupling

96 rotor (fourth rotator)

56 shaft section

87, 114 slider

91, 111 body

114 a hub (engaging portion)

114 b groove (engaging portion)

116 receiving hole 

1. A fluid machine comprising: a plurality of fluid units each including a rotator and configured to let in and out a working fluid as the rotator rotates; and a drive shaft to which the rotators of said plurality of fluid units are coupled, wherein an Oldham coupling is arranged at a shaft section of the drive shaft located between the rotators.
 2. The fluid machine according to claim 1, wherein: the Oldham coupling includes a slider, the slider having an engaging portion for engagement with the shaft section and a body provided with the engaging portion, and the slider is received in a receiving hole formed in the shaft section.
 3. The fluid machine according to claim 2, wherein said plurality of fluid units include an expansion unit, the expansion unit including a first rotator and configured such that as the first rotator rotates, the expansion unit admits the working fluid, then expands the working fluid, and delivers the expanded working fluid.
 4. The fluid machine according to claim 2, wherein said plurality of fluid units include a pump unit, the pump unit including a second rotator and configured such that as the second rotator rotates, the pump unit draws in the working fluid, then raises pressure of the working fluid, and discharges the working fluid.
 5. The fluid machine according to claim 2, wherein said plurality of fluid units include a compression unit, the compression unit including a third rotator and configured such that as the third rotator rotates, the compression unit draws in the working fluid, then compresses the working fluid, and delivers the compressed working fluid.
 6. The fluid machine according to claim 2, further comprising an electric power generation unit including a fourth rotator coupled to the drive shaft, wherein the electric power generation unit is configured to generate electric power as the fourth rotator rotates.
 7. The fluid machine according to claim 2, further comprising a power generation-drive unit including a fifth rotator coupled to the drive shaft, wherein the power generation-drive unit is configured to generate electric power as the 2fifth rotator rotates, and to drive the drive shaft when the fifth rotator is rotated by externally supplied electric power.
 8. The fluid machine according to claim 2, further comprising a motive power transmission unit coupled to the drive shaft and configured to transmit motive power between the drive shaft and an external device. 